bpo-21417: Add compresslevel= to the zipfile module (GH-5385)

This allows the compression level to be specified when writing zipfiles
(for the entire file *and* overridden on a per-file basis).

Contributed by Bo Bayles

1 files changed, 35 insertions, 8 deletions

diff --git a/Lib/zipfile.py b/Lib/zipfile.py
index 37ce3281e0..f9db45f58a 100644
--- a/Lib/zipfile.py
+++ b/Lib/zipfile.py
@@ -295,6 +295,7 @@ class ZipInfo (object):
         'filename',
         'date_time',
         'compress_type',
+        '_compresslevel',
         'comment',
         'extra',
         'create_system',
@@ -334,6 +335,7 @@ class ZipInfo (object):
 
         # Standard values:
         self.compress_type = ZIP_STORED # Type of compression for the file
+        self._compresslevel = None      # Level for the compressor
         self.comment = b""              # Comment for each file
         self.extra = b""                # ZIP extra data
         if sys.platform == 'win32':
@@ -654,12 +656,16 @@ def _check_compression(compression):
         raise NotImplementedError("That compression method is not supported")
 
 
-def _get_compressor(compress_type):
+def _get_compressor(compress_type, compresslevel=None):
     if compress_type == ZIP_DEFLATED:
-        return zlib.compressobj(zlib.Z_DEFAULT_COMPRESSION,
-                                zlib.DEFLATED, -15)
+        if compresslevel is not None:
+            return zlib.compressobj(compresslevel, zlib.DEFLATED, -15)
+        return zlib.compressobj(zlib.Z_DEFAULT_COMPRESSION, zlib.DEFLATED, -15)
     elif compress_type == ZIP_BZIP2:
+        if compresslevel is not None:
+            return bz2.BZ2Compressor(compresslevel)
         return bz2.BZ2Compressor()
+    # compresslevel is ignored for ZIP_LZMA
     elif compress_type == ZIP_LZMA:
         return LZMACompressor()
     else:
@@ -963,7 +969,8 @@ class _ZipWriteFile(io.BufferedIOBase):
         self._zinfo = zinfo
         self._zip64 = zip64
         self._zipfile = zf
-        self._compressor = _get_compressor(zinfo.compress_type)
+        self._compressor = _get_compressor(zinfo.compress_type,
+                                           zinfo._compresslevel)
         self._file_size = 0
         self._compress_size = 0
         self._crc = 0
@@ -1035,7 +1042,8 @@ class _ZipWriteFile(io.BufferedIOBase):
 class ZipFile:
     """ Class with methods to open, read, write, close, list zip files.
 
-    z = ZipFile(file, mode="r", compression=ZIP_STORED, allowZip64=True)
+    z = ZipFile(file, mode="r", compression=ZIP_STORED, allowZip64=True,
+                compresslevel=None)
 
     file: Either the path to the file, or a file-like object.
           If it is a path, the file will be opened and closed by ZipFile.
@@ -1046,13 +1054,19 @@ class ZipFile:
     allowZip64: if True ZipFile will create files with ZIP64 extensions when
                 needed, otherwise it will raise an exception when this would
                 be necessary.
+    compresslevel: None (default for the given compression type) or an integer
+                   specifying the level to pass to the compressor.
+                   When using ZIP_STORED or ZIP_LZMA this keyword has no effect.
+                   When using ZIP_DEFLATED integers 0 through 9 are accepted.
+                   When using ZIP_BZIP2 integers 1 through 9 are accepted.
 
     """
 
     fp = None                   # Set here since __del__ checks it
     _windows_illegal_name_trans_table = None
 
-    def __init__(self, file, mode="r", compression=ZIP_STORED, allowZip64=True):
+    def __init__(self, file, mode="r", compression=ZIP_STORED, allowZip64=True,
+                 compresslevel=None):
         """Open the ZIP file with mode read 'r', write 'w', exclusive create 'x',
         or append 'a'."""
         if mode not in ('r', 'w', 'x', 'a'):
@@ -1066,6 +1080,7 @@ class ZipFile:
         self.NameToInfo = {}    # Find file info given name
         self.filelist = []      # List of ZipInfo instances for archive
         self.compression = compression  # Method of compression
+        self.compresslevel = compresslevel
         self.mode = mode
         self.pwd = None
         self._comment = b''
@@ -1342,6 +1357,7 @@ class ZipFile:
         elif mode == 'w':
             zinfo = ZipInfo(name)
             zinfo.compress_type = self.compression
+            zinfo._compresslevel = self.compresslevel
         else:
             # Get info object for name
             zinfo = self.getinfo(name)
@@ -1575,7 +1591,8 @@ class ZipFile:
                 raise LargeZipFile(requires_zip64 +
                                    " would require ZIP64 extensions")
 
-    def write(self, filename, arcname=None, compress_type=None):
+    def write(self, filename, arcname=None,
+              compress_type=None, compresslevel=None):
         """Put the bytes from filename into the archive under the name
         arcname."""
         if not self.fp:
@@ -1597,6 +1614,11 @@ class ZipFile:
             else:
                 zinfo.compress_type = self.compression
 
+            if compresslevel is not None:
+                zinfo._compresslevel = compresslevel
+            else:
+                zinfo._compresslevel = self.compresslevel
+
         if zinfo.is_dir():
             with self._lock:
                 if self._seekable:
@@ -1617,7 +1639,8 @@ class ZipFile:
             with open(filename, "rb") as src, self.open(zinfo, 'w') as dest:
                 shutil.copyfileobj(src, dest, 1024*8)
 
-    def writestr(self, zinfo_or_arcname, data, compress_type=None):
+    def writestr(self, zinfo_or_arcname, data,
+                 compress_type=None, compresslevel=None):
         """Write a file into the archive.  The contents is 'data', which
         may be either a 'str' or a 'bytes' instance; if it is a 'str',
         it is encoded as UTF-8 first.
@@ -1629,6 +1652,7 @@ class ZipFile:
             zinfo = ZipInfo(filename=zinfo_or_arcname,
                             date_time=time.localtime(time.time())[:6])
             zinfo.compress_type = self.compression
+            zinfo._compresslevel = self.compresslevel
             if zinfo.filename[-1] == '/':
                 zinfo.external_attr = 0o40775 << 16   # drwxrwxr-x
                 zinfo.external_attr |= 0x10           # MS-DOS directory flag
@@ -1648,6 +1672,9 @@ class ZipFile:
         if compress_type is not None:
             zinfo.compress_type = compress_type
 
+        if compresslevel is not None:
+            zinfo._compresslevel = compresslevel
+
         zinfo.file_size = len(data)            # Uncompressed size
         with self._lock:
             with self.open(zinfo, mode='w') as dest: